1. Field of the Invention
The present invention relates to an image forming apparatus such as copiers and printers. More particularly, the invention relates to an image forming apparatus wherein a variety of cartridges containing therein various consumables, such as an imaging cartridge containing a toner, are removably loaded in an apparatus body.
2. Description of the Related Art
Conventionally, the image forming apparatuses such as the copiers and printers employ the various cartridges containing therein a variety of consumables, such as the imaging cartridge containing the toner. Such cartridges are removably loaded in the apparatus body.
When the various cartridges such as the imaging cartridge are replaced, such an image forming apparatus must take a procedure for determining the type and status of the cartridge to be replaced so as to make sure that a proper cartridge is loaded in the apparatus body. The determination is made on, for example, the color of the toner contained in the cartridge, the toner content, information on the replacement product, consumption information and the like. To meet this purpose, a constitution is made, for example, such that the cartridge and a cartridge mounting portion of the image forming apparatus are configured to conform to each other to permit only a proper cartridge to be loaded. Otherwise, the cartridge is provided with a fuse for determining whether the replacement cartridge is a fresh product or not.
However, if the aforementioned determination mechanism is provided in all types of cartridges, an increased cost results.
In order to provide for a low-cost determination of the types of all the cartridges, it has become a practice to install a memory in every one of the cartridges and to write cartridge-specific information in the memory at factory shipment, the information indicating the type and specifications of the cartridge. In this connection, an image forming apparatus operating as follows has been proposed. When this cartridge is loaded in the image forming apparatus, the apparatus retrieves the information written in this memory so as to determine the type of the cartridge and then, performs an operation suited to the type of the cartridge.
However, the measure to install the memories in all the cartridges still involves the problem of cost increase.
More recently, an image forming apparatus directed to the cost reduction of a photosensitive cartridge has been proposed (Japanese Unexamined Patent Publication No. 2004-341283). In this apparatus, consumption information on a photosensitive member is stored in the imaging cartridge instead of installing the memory in the photosensitive cartridge accommodating the photosensitive member, and determination is made on the life end of the photosensitive member.
However, in a case where there are plural imaging cartridges individually containing toners of different colors in different quantities, for example, it is necessary to prevent the individual cartridges from being mistakenly loaded in improper places.
Furthermore, the replacement of the aforementioned cartridges may involve the following problem. That is, a new replacement cartridge may be subjected to various improvements. In some cases, the characteristic or the like of the toner contained in the replacement cartridge may be subjected to some minor change such as to permit an alternative image forming apparatus to share the cartridge and hence, the toner contained in the replacement cartridge at factory shipment may have a slightly varied characteristic from that of the toner contained in the in-use cartridge.
In a case where such a new cartridge containing therein the toner having somewhat varied characteristic is loaded in the image forming apparatus, the apparatus must be controlled according to the varied characteristic of the toner.
On this account, all the cartridges such as the above imaging cartridge normally carry the memories which store the characteristic of the toner contained in the cartridge and such, thereby permitting the image forming apparatus to perform image formation under proper image forming conditions. Consequently, the problem of the increased cost of the cartridge still remains unsolved.